Early March snow looking more likely, but accumulation uncertain

Meteorologists watching forecast models for a potential mid-week snowfall are gaining confidence that a developing storm could affect Maryland, but whether it will bring significant snow accumulation remains uncertain.

Models were showing late Saturday an area of low pressure likely to reach the region Tuesday night through Wednesday, potentially packing a large amount of moisture. As with many storm systems to pass through this winter, it was not immediately clear where that water might fall as rain and where as snow.

On Sunday night, the National Weather Service's look ahead for the greater Baltimore area called for rain or snow likely on Tuesday night, with lows in the mid-30s and a 70 percent chance of precipitation.

Heading into Wednesday, that chance increased to 80 percent, with highs predicted to be in the upper 30s. Snow was likely into Wednesday night, according to the NWS.

A run of the U.S. government's GFS model Saturday afternoon was calling for significant snowfall centered over Maryland and the mid-Atlantic for the middle of the week. But long-range models of more than a few days out from a potential snow event have been notoriously unreliable and prone to change this season, local forecasters said.

The weather service's Hydrometeorological Prediction Center, soon to go by the name Weather Prediction Center, suggests "multiple sources of uncertainty" causing forecast models to show "significant spread and run to run variability."

Its forecast maps showed, as of Saturday afternoon, just slim chances of a light snow for Central Maryland on Tuesday. Wednesday's precipitation odds were not scheduled to be in its forecast mapping window until sometime Sunday.

The weather service's local forecasters showed similar hesitance.

"THERE IS STILL TOO MUCH UNCERTAINTY THIS FAR OUT TO ATTEMPT TO PIN DOWN SPECIFIC IMPACTS," the meteorologists wrote in a forecast discussion Saturday afternoon. "THE STORM IS STILL OVER THE NRN PACIFIC OCEAN...WHERE MODELS DO NOT INITIALIZE THE ATMOSPHERE AS WELL...THUS LIKELY CONTRIBUTING TO A FAIR AMOUNT OF RUN TO RUN MODEL INCONSISTENCIES."

But other professional and amateur meteorologists are suggesting it could be the region's best chance for a significant snowfall.

The meteorologist who goes by @wxmanmd on Twitter and blogs on local conditions for the Weather Underground suggests the system is worth watching. Its worst-case scenario could mean as much as a foot of snow, he suggests. But given how poorly long-term models have performed this winter, busting in the face of big storm forecasts, he cautions skepticism.

Foot's Forecast said given "flip-flopping" models, the chances for significant snow or no precipitation at all are about as good as "a coin flip, at best."